The question has been asked so often at broadcasting conferences, in management consultancy reports and at boardroom tables that it is teetering on the brink of cliche. But it is still the one most likely to keep TV executives awake at night staring at the ceiling. In an age of exploding digital choice, are we witnessing the death throes of mass-market, linear television channels?

The last year has felt pivotal. The proliferation of high-speed broadband connections, the growth in PVR ownership, the popularity among young audiences of web 2.0 phenomena like YouTube and MySpace and the imminent launch of a plethora of video on demand services both from broadcasters and new aggregators like Apple and Google have accelerated the rate of change.

Meanwhile, broadcasters are also having to come up with new ways of defining success in a world where revenue from "long tail" archive shows could become as important as prime-time event programming. At Thursday's Royal Television Society conference in London, the great and the good wrestled again with the implications of a digital future racing towards them at alarming speed.

CBS chief executive Leslie Moonves offered an optimistic vision: "We don't care how you get your content. By cable, over the air, over a telephone wire. We are going to get paid for that content over and over and over again." When outgoing ITV chief executive Charles Allen claimed it could pull off the same trick, no one looked convinced. But overall the mood was more upbeat than might have been expected given gloomy ad market predictions and changing media consumption habits.

MediaGuardian asked leading players whether the rise of digital would lead to the death of linear broadcasting, and what they were going to do about it.

Charles Allen

Outgoing chief executive, ITV

I think we'll still have linear broadcasting in 20 years' time. It will be different and the viewer might be more involved in how that linear broadcast is put together. But people will still want to be led to programmes. You want to be entertained and you don't know what our latest big hit is. If you think about a supermarket, it's their job to bring you new products. If you only chose things you'd had before you'd never try anything new. Tesco do value brands and they do Tesco Finest. It's accessible to everyone and you take away what you want. The broadcast brands of the future will be the same.

Andy Duncan

Chief executive, Channel 4

Linear channels will remain the most important thing but they're no longer going to be sufficient. A combination of smaller channels, new platforms and timeshifting via PVR or broadband change the landscape very significantly. For some audiences and channels those things matter very little. For other audiences they matter a lot.

Channels are not dying but they've got to learn to be a lot more flexible. It's happening pretty rapidly. Multichannel is already there and broadband is growing fast. There'll be a significant minority, of younger audiences in particular, who will be timeshifting a lot more of their programming within two or three years.

Duncan Gray

Head of entertainment, ITV

I think it is wrong to give up on the idea that you can have big hits, even in a world where audiences are eroding. Network television can make things on a huge scale, we have the production expertise. We have to think about our TV shows in a different way, the way the US studios do, develop the hell out of them, execute the hell out of them.

Look at The X Factor. It is remarkable working with Simon Cowell. We all sat down four months ago, at Simon's house, it was so refreshing to work out how to make this year's third series even better. We are upping the story levels, making material changes to the studio. You also measure a hit show, not just by the metrics, but by its cultural impact.

Janice Hughes

Chief executive, Spectrum Consultants

Do I believe that linear television channels will disappear in five to 10 years? No. But it is difficult if you can't be certain. We appear to be moving into a world where everything is provided for free. The premise is based on advertisers being there to support things. But if the audiences do move off, to Bebo or YouTube, then that is going to make it difficult if the revenue follows them. As for Channel 4, it probably needs to have really strong partnerships with independent producers, so they don't leave.

Luke JohnsonChairman, Channel 4

It is always difficult predicting anything even a few years ahead in business, and the difficulty is even greater with TV, where things are changing at an unprecedented rate.

Looking at the audience declines this autumn and peak-time audience ratings, it is hard to see things going on in the same way. There is also a change in the kinds of programmes channels are now starting to run in peak time.

Alex GrahamChief executive, Wall to Wall Television

Oh for goodness sake, I think that every time there is a new technology people predict the death of the old one, but movies didn't kill off newspapers, television didn't kill off the cinema, video didn't kill off television, and nor did DVDs, and the internet will not kill off television networks either.

Television will still be here as we know it in ten years' time. I think there is as much chance of television being dead as there is of Gordon Brown becoming prime minister.

James MurdochChief executive, BSkyB

If you think of the move from 40 channels to 400 there was a very similar trend. I'm not sure it's about on demand versus broadcast channels. They both contribute to that flexibility.

Mark ThompsonDirector general, BBC

What I said at Banff [in 2000] is that I thought the channels most likely to succeed were those that were thematically focused or attitudinally focused.

If you look at the US and what Les [Moonves] has done with CBS and if you look at the continuing success of BBC4 [that's borne out]. With ITV, one of the issues with it is: what's its attitudinal profile and what's its flavour and in what kind of zone does the content fit?

Channels are fundamentally powerful marketing battering rams and creators of hit programmes and key talent. I think that role is going to continue. But whereas once channels were everything, there are manifestly other ways of getting content.

Even a timeshifted channel is quite different from a traditional channel. Instead of two to three hours of drama, you've got 80. Our belief is that this business of an attitudinal feel and flavour, based around the branding of the channel, will still be a force away from linear programming.

Jamie KantrowitzVice president of content and marketing, MySpace Europe

I don't think that we are seeing the death of linear broadcasting, we're seeing a change in programming to something which is multi-platform. We're seeing a correction in linear broadcasting.